Is sound "additive"?


If I kept adding speakers playing at say, 70 db to a particular room, would the sound keep increasing? Wierd question, but I was thinking about how it sounds when a room fills up and people are talking -- it just gets louder and louder (though some of this is can be attributed to people speaking louder to compensate for others' talking). I was going to try and relate this to the effect (in SPL) of adding multiple subs to a room. Would it just keep getting louder and louder?
128x128felthove
liguy, there is no theoretical reason why a properly set-up 2-channel subwoofer system would not be in phase - unless one subs' speaker leads were hooked up backwards from the other - just like w/a pair of regular full-range speakers, being driven by a stereo amp. of course, you could also have your subs out-of-phase from your monitors, if the subs' leads were reversed relative to the monitors', but this mix-up is also possible w/a single sub. in fact, assuming proper connections, there's actually a chance of signal-cancellation when using only *one* sub, w/the two-channel signal summed to mono. in this set-up, there's the possibility of left/right-channel signal cancellation...

regards, doug s.

btw, the proper reason to use two subs in a system instead of one, is *not* to increase the spl of the bass - this wood only make the sound too bass-heavy in relation to your monitors. as said before, a second sub allows the *same* spl's w/reduced distortion, as well as improving imaging/soundstaging.

doug s.

Sedond, agreed! I was only pointing out that the answer to the question is not simple. In order for sound to be perfectly additive they must be exactlt in phase. If they are a degree or 2 different the sum will be different. I made no attempt to relate this to a subwoofer.